ACTIVE TRIAC TRIGGERING CIRCUIT

• US 20180048300A1
• Filed: 10/24/2017
• Published: 02/15/2018
• Est. Priority Date: 04/23/2013
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Landry, Daniel, Tousignant, Daniel, Daher, Alex, Lussier, Marco
• Granted Patent: US 10,396,770 B2
• Time in Patent Office: Days
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 1/44 Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
• CPC Class Codes: H02M 5/257 using semiconductor devices only
• CPC Class Codes: H03K 17/00 Electronic switching or gating, i.e. not by contact-making and –breaking gated amplifiers H03F3/72; switching arrangements for exchange systems using static devices H04Q3/52
• CPC Class Codes: H03K 17/136 in thyristor switches
• CPC Class Codes: H03K 17/725 for ac voltages or currents H03K17/722, H03K17/735 take precedence
• CPC Class Codes: H03K 2217/0081 Power supply means, e.g. to the switch driver

Abstract

A power supply unit for use with thermostats or other like devices requiring power. A power supply unit may be designed to keep electromagnetic interference emissions at a minimum, particularly at a level that does not violate governmental regulations. A unit may be designed so that there is enough power for a triggering a switch at about a cross over point of a waveform of input power to the unit. Power for triggering may come from a storage source rather than line power to reduce emissions on the power line. Power for the storage source may be provided with power stealing. Power stealing may require switching transistors which can generate emissions. Gate signals to the transistors may be especially shaped to keep emissions from transistor switching at a minimum.

Claims

1. A power supply unit for a heating, ventilation and air conditioning thermostat, comprising:

a first terminal for connection to a line of a power source;

a second terminal for connection to a load;

a bypass circuit having an input connected to the first terminal;

a triac having an input connected to the first terminal;

a stealing circuit having an input connected to an output of the bypass circuit and having an output connected to the second terminal;

a power steal module having an input connected to an output of the triac; and

a drive circuit having an output connected to a second input of the power steal module.

2. The unit of claim 1, further comprising a zero crossing detection circuit having an input connected to the first terminal and an output connected to an input of the drive circuit.

3. The unit of claim 1, further comprising:

a zero crossing detection circuit having an input connected to the first terminal; and

the zero crossing detection circuit having an output connected to a central processing unit (CPU).

4. The unit of claim 1, wherein a second output of the stealing circuit is connected to a second input of the drive circuit.

5. The unit of claim 4, wherein:

the stealing circuit comprises an energy storage; and

stored energy goes from the second output of the stealing circuit to the second input of the drive circuit.

6. The unit of claim 5, wherein the energy storage is always active.

7. The unit of claim 1, further comprising a trigger circuit having an output connected to an input of the drive circuit.

8. The unit of claim 1, further comprising:

a zero crossing detection circuit having a half wave zero crossing detector; and

a trigger circuit comprising;

a DC-DC negative current source having an input connected to a second output of the stealing circuit; and

a triac gate triggering signal circuit having an input connected to an output of the DC-DC negative current source.

9. The unit of claim 1, further comprising:

a DC-DC converter connected to the output of the stealing circuit; and

wherein the bypass circuit comprises an AC-DC converter.

10. A power system for thermostats, comprising:

a first terminal connected to a line of a power supply;

a bypass circuit having an input connected to the first terminal;

a triggerable switch having an input connected to the first terminal;

a power steal module having a first input connected to an output of the bypass circuit and a second input connected to the first terminal, the power steal module is configured to steal power from the bypass circuit or the first terminal;

an energy storage module having an input connected to an output of the power steal module for receiving stolen power from the power steal module; and

a processor having an input connected to an output of the energy storage module and having an output connected to a second input of the triggerable switch.

11. The system of claim 10, wherein the power steal module is configured to be active when a thermostat is in an on state and when the thermostat is in an off state.

12. The system of claim 10, wherein the power steal module is configured to be active when a thermostat is in an on state and inactive when the thermostat is in an off state.

13. The system of claim 10, further comprising:

a zero crossover detector having an input connected to an output of the bypass circuit and an output connected to an input of the processor; and

wherein the processor determines a drive signal for the triggerable switch from a zero crossing signal of the output of the zero crossover detector and from a set of instructions.

14. The system of claim 13, wherein power is taken from the energy storage module and used to trigger the triggerable switch near a zero crossing of energy on the line of the power supply as effected by the processor and a line pattern according to a working quadrant of the triggerable switch.

15. The system of claim 13, further comprising:

a gate signal shaper having an input connected to an output of the zero crossover detector and having an output connected to the power steal module; and

wherein the power steal module comprises one or more MOSFETs.

16. The system of claim 15, wherein an output of the gate signal shaper is a gate signal having a shape that switches the one or more MOSFETs on or off in a manner to minimize EMI emissions from switching stolen power by the one or more MOSFETs.

17. The system of claim 15, further comprising a MOSFET reverse wave protection circuit having an input connected to the first terminal and an output connected to a second input of the gate signal shaper.

18. A thermostat power system comprising:

a triggerable switch having an input connected to a first terminal;

a bypass circuit having an input connected to the first terminal;

an energy storage module having an input connected to an output of the bypass circuit and an output connected to a second terminal;

a power steal circuit having an input connected to an output of the triggerable switch; and

an active trigger module having an output connected to the triggerable switch and an input connected to a second output of the energy storage module for taking energy from the energy storage module to trigger the triggerable switch.

19. The system of claim 18, wherein the first terminal and second terminal are for connection to an AC power line and load arrangement.

20. The system of claim 18, further comprising:

a wave position detector having an output connected a second input of the active trigger module; and

wherein;

a trig signal is sent at certain times, according to information at the output of the wave position detector, from the output of the active trigger module to a second input of the triggerable switch;

a signal from the output of the triggerable switch to the input of the power steal circuit turns the power steal circuit on off; and

the active trigger module takes energy at a second input from the second output of the energy storage module to trigger the triggerable switch near a zero crossing of a power line in communication with the first terminal and the second terminal when energy directly from the power line is insufficient to trigger the triggerable switch.